/*
 * Copyright (c) 2023-2020 elsfs Authors. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.elsfs.cloud.handler;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.elsfs.cloud.common.core.vo.R;
import org.springframework.boot.web.reactive.error.ErrorWebExceptionHandler;
import org.springframework.core.annotation.Order;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.http.MediaType;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.server.ResponseStatusException;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.handler.ResponseStatusExceptionHandler;
import reactor.core.publisher.Mono;

/** 网关异常通用处理器，只作用在webflux 环境下 , 优先级低于 {@link ResponseStatusExceptionHandler} 执行 */
@Slf4j
@Order(-1)
@RequiredArgsConstructor
public class GlobalExceptionHandler implements ErrorWebExceptionHandler {

  private final ObjectMapper objectMapper;

  @Override
  public Mono<Void> handle(ServerWebExchange exchange, Throwable ex) {
    ServerHttpResponse response = exchange.getResponse();

    if (response.isCommitted()) {
      return Mono.error(ex);
    }

    // header set
    response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
    if (ex instanceof ResponseStatusException) {
      response.setStatusCode(((ResponseStatusException) ex).getStatusCode());
    }

    return response.writeWith(
        Mono.fromSupplier(
            () -> {
              DataBufferFactory bufferFactory = response.bufferFactory();
              try {
                LOGGER.debug(
                    "Error Spring Cloud Gateway : {} {}",
                    exchange.getRequest().getPath(),
                    ex.getMessage());
                return bufferFactory.wrap(objectMapper.writeValueAsBytes(R.error(ex.getMessage())));
              } catch (JsonProcessingException e) {
                LOGGER.error("Error writing response", ex);
                return bufferFactory.wrap(new byte[0]);
              }
            }));
  }
}
